|
|
| 1 |
Microwave Questions / Antennas / SIW Antenna
on: Today at 16:51:09 |
| Started by gundam17 | Post by gundam17 |
Hi All,
I'm trying to design a SIW slot antenna on alumina. I can't for the life of me get it to work. I've designed many in the past, and know the standard design methodology. In fact, I designed a similar antenna on a lower dielectric constant substrate, and it worked like a champ.
Any leads to why it wouldn't work on alumina?
-Sam |
  
|
| 2 |
Microwave Questions / Modeling and System Design / Re: AGC Modeling in MWO or VSS
on: Today at 14:07:54 |
| Started by ml2392 | Post by madengr |
You need to produce an error signal by subtracting the detector signal from fixed set-point; try the DIFF element You then integrate the error signal to drive the attenuator (or VGA); try the INTGRL element followed by a DLY_SMP to keep the simulator happy. The feedback servos the loop until zero error. Standard old control theory applies; check step response, frequency response, etc.
I used an op-amp based integrator in the circuit simulator then implemented it in VSS using the LIN_S element. However I just replaced it will the elements described above but it slowed to a crawl; don't fully trust the INTGRL element.
You really need to tweak the _DRATE and _SMPSYM in the document options to get it working good. |
|
|
| 4 |
Microwave Questions / Circuit Design and Layout / 10.7 MHz, monolithic, ceramic IF Filter
on: Today at 13:12:35 |
| Started by antennafarmer | Post by antennafarmer |
Hello,
Is anyone familiar with Mil/Aviation rated IF Filter manufacturer?
I want to replace Murata SFE10.7MS3G-A which had flat group delay and went obsolete. Any ideas?
TNX |
|
|
| 5 |
Microwave Questions / Modeling and System Design / Re: CST Genetic Algorithm Setting Problem
on: Today at 12:52:49 |
| Started by winson | Post by MikeSaunders |
Winson,
Genetic Algorithm, yikes! I think nobody has answered your question because there is a small amount of information in your post.
16 parameters, sounds like an array maybe? If it is a 'normal' design then a different optimizer like Nelder-Mead will work well. GA requires a wide breadth and a good number of generations to have confidence in the optimization. And I know, if you're at a university, the atmospheric sciences department buys up all the computing time, and if you're at work, work won't pay for good computational capability. How long does one solve take? |
|
|
| 6 |
Microwave Questions / Modeling and System Design / Re: AGC Modeling in MWO or VSS
on: Today at 09:53:19 |
| Started by ml2392 | Post by ml2392 |
In VSS, I'm using detector HMC662LP3 and the measured Log Out voltage is between 1 to 1.75V over an input dynamic range of 50dB (0 to -50dBm). The measured data is stored in a LUT.
As for VGA, I am using VGA_F with measured data of Avago ALM-80210. The control voltage of this VGA is from 0 to 5V.
In reality, the output of the detector is feed into an ADC, then to a FPGA, and out to a DAC which outputs a control voltage range of 0 to 3.3V.
Question: How do I accurately map the measured detector voltage to the control voltage of the VGA_F in VSS?
Thanks, |
|
|
| 9 |
Microwave Questions / Measurement, Test, and Characterization / Re: Combine 2-port VNA-measurements of a 8-port-de
on: Yesterday at 18:29:43 |
| Started by malvinas2 | Post by madengr |
Ha! Dave beat me to it. What a hair puller. Yeah, it becomes a mess real quick if you need to arbitrarily choose any column for the new file, especially cross port responses. I ended up using VCVS to split the signals and VCCS terminating the circulators to provide the proper termination for reflection and to inject the reverse signal. Never did put in the S32 and S13 paths; got too frustrated. I think if one takes the time to draw out the signal flow graph it would be clearer.
AWR does have a procedure but it doesn't seem straight-foward either:
https://awrcorp.com/download/faq/english/docs/Users_Guide/ch03s03s03.html
|
|
|
| 10 |
Microwave Questions / Measurement, Test, and Characterization / Re: Combine 2-port VNA-measurements of a 8-port-de
on: Yesterday at 15:55:25 |
| Started by malvinas2 | Post by Dave |
Hi Malvinas,
I'm not aware of any fully automated way to do it, unless you can get access to an 8-port VNA somehow  You could talk to your local Agilent/R&S rep and see if they have any software tools for combining the results.
After a quick experiment in Microwave Office, you can combine the files there in a semi-automated manner, and I assume ADS will be similar. You basically need to put down all your s2p files as subcircuit elements and link them up with isolators/circulators. This gets very messy very quickly though, and for an s8p file you're going to have a real rats-nest of wires linking elements - lots of opportunity for mistakes!
I think your best approach is to write a script in Matlab or GNU Octave (open-source Matlab equivalent) that can read in the s2p files and assign the right source columns of each s2p to the right destination column of your s8p. Otherwise, manual might be the only way to do it.
Hope this helps,
Dave |
|
|
|
|
